Abrasive throwing machine



NOV. 25, 1941. HUGHES 2,264,265

ABRASIVE THROWING MACHINE Filed April 20, 1958 4 Shee'ts-Sheet 1 ATTORNEY Nov. 25, 1941. E. R. HUGHES ABRASIVE Pl-[ROWING MACHINE Filed April 20, 1938 4 Sheets-Sheet 2 his . ljgENTOR [rig/ arr! if y ATTORNEY Nov. 25, 1941. R. HUGHES ABRAS IVE THROWING MACHINE Filed April 20, 1938 4 Sheets-Sheet 3 INVENTOR iduldrdfil lgfies ATTORNEY Nov. 25, 1941.

E. R. HUGHES ABRASIVE THROWING MACHINE Filed April 20, 1938 4 Sheets-Sheet 4 ATTORNEY Patented Nov. 25, 1941 2,264,265 4 ABRASIVE 'rnaowmc. MACHINE lidward R. Hughes, Morristown, N. 3., assignor to The American Foundry Equipment Company, Mishawaka, Ind., a corporation of Delaware Application April 20, 1938, Serial No. 203,019

11 Claims.

This invention relates to abrasive throwing machines and more particularly to abrasive throwing machines of the rotary, centrifugal type having means associated therewithfor controlling the direction of flight of the thrown abrasive.

In accordance with the present invention, there is provided a rotary centrifugal throwing wheel comprising a plurality of spaced throwing blades extending inwardly from the periphery. of the wheel toward the axis of rotation and suitably mounted for rotation about the axis. Feeding means for delivering abrasive to the blades at the desired location and under suitable control are provided and include a conduit or duct having a discharge opening located in suitable relation with the rotatable blades. Positive feeding means for urging the abrasive along the conduit or duct is provided and includes a rotatable impeller having one or more vanes rotatable independently of the throwing blades of the wheel. The impeller is suitably driven independently of the throwing blades in order to eject abrasive at controlled, adjustable velocity through the opening of the feed conduit or duct in a suitable direction and at a suitable velocity. The conduit or duct preferably is mounted for adjustment relative to the throwing blades whereby the direction of flight of abrasive from the throwing blades can be adjusted and controlled.

An object of the present invention is to provid an abrasive throwing machine of the rotary centrifugal type having improved means for feeding abrasive to the throwing blades.

Another object of the invention is the provision of a rotary centrifugal throwing wheel having means for feeding abrasive to the throwing blades at a rate and velocity which can be controlled and adjusted independently of the speed of rotation of the throwing blades.

Still another object of the invention is the provision of a rotary centrifugal throwing wheel having an improved device for feeding abrasive onto the throwing blades in a general radial direction and with an initial velocity in the direction of rotation of the wheel.

Various other features and advantages of the invention will be apparent from the following particular description and from an inspection of the accompanying drawings.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connec- I tion with the accompanying drawings forming a part thereof, in which Fig. 1 is a front elevational view of an abrasive throwing machine constructed in accordance with the present invention;

Fig. 2 is a vertical sectional view taken along line 2-2 of Fig. 1;

Fig. 3 is a view similar to Fig. 1 except in that certain of the parts are shown in section to illustrate certain details of the construction;

Fig. 4 is a, verticalsectional view taken along line 4-4 of Fig. 2;

Fig. 5 is a fragmentary vertical cross-sectional view of the device shown in Figs. 1 to 4 and illustrating a difierent adjustment of the control device, whereby the abrasive is hurled in a direction generally opposite to that provided by the adjustment illustrated in Figs. 1 to 4;'

Fig. 6 is a front elevational view illustrating a machine constructed in accordance with another embodiment of the invention;

Fig. 7 is a vertical cross-sectional view taken along line 1-1 of Fig. 6;

Fig. 8 is a front elevational view of the construction shown in Fig. 6, the control device being shown, however, in a position of adjustment for throwing the abrasive in a direction intermediate that provided by the adjustment illustrated in Figs. 6 and 9;

Fig. 9 is a vertical cross-sectional view generally similar to Fig. 7 only showing the control device adjusted to a position in a direction generally opposite that shown in Figs. 6 and 7;

Fig. 10 is a front elevational view of another embodiment of the invention, certain of the parts being broken away and sectioned in order to 11- lustrate certain details of construction;

In the following description and in the claims,

various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit. Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification, certain specific disclosure of the invention .is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring now particularly to Figs. 1 to 4, there is shown an abrasive throwing machine of the rotary, centrifugal type constructed in accordance with the invention. The machine comprises a rotor including a disc or side wall 2 carrying a plurality of throwing blades 3. The side wall is carried on a shaft 4 by a suitable mounting member or hub 3 to which the side wall is attached as by bolts 3. A second side wall I may be provided and is suitably secured to the first side wall 2, as by a stud 8 having reduced ends inserted in the side walls 2 and I and suitably secured thereto. The blades are suitably secured in place, as by one or more set screws 3 extending through one of the side walls and entering recesses [3 in the blades. Preferably, the blades are formed with side flanges 3' which seat in suitably positioned grooves 2' and I in the inner faces of the side walls 2 and I respectively.

The throwing blades 3 may extend from adjacent the periphery of the rotor toadjacent the axis of rotation, and, in the present embodiment, the blades 3 terminate short of the axis to provide a central space 23. For guiding the abrasive into the path of the throwing blades, a deflector II, of generally peaked form and having a cylindrical base I2, is disposed in the central space 23. The deflector H is seated in an opening in the side wall 2 and secured as by bolts, whereby the deflector II is carried by the side wall 2 for rotation with the throwing blades 3. For the purpose of assisting in guiding the abrasive onto the throwing blades, the deflector II is provided with one or more deflector vanes 3, which preferably correspond in number and general location to the throwing blades 3, but which angularly' lead the blades 3 a slight amount, as indicated in Fig. 4.

The base I2 of the deflector closes the inner ends of the grooves 2' and provides an inner abutment for the blades 3. The side wall I may be provided with a shoulder 4 also providing an inner abutment for the blades 3.

The side wall I is formed with a generally circular opening 43 defined by an outwardly flared rim 4|, through which opening abrasive can be supplied to the rotor l. The inner ends of the deflector vanes |3 terminate in an arcuate edge defining with the edges of the rim 4| a dished or arced recess.

Abrasive is delivered to the rotor I through a conduit or duct which includes a control device l3 having a discharge outlet disposed closely adjacent the deflector and offset radially from the axis of rotation of the rotor. The control device includes a suitable housing 43 having an extension or spout l3 extending up to the opening 43 in the side wall I and defining the discharge outlet H.

The housing 43 is suitably mounted on a bracket 23 which is preferably mounted for angular adjustment. For example, the bracket 23 is provided with a stud 2| journaled in a flxed bearing member 22 and positioned therein as by a set screw 23. The bearing 22 is suitably fixed to a stationary member (not shown) so as to be rigidly held relative to the rotor If desired, additional support for the bracket 20 may be provided in the form of a stud 33 extending from the bracket 23 and secured by adjustable means to any desired point in an arcuate or circular member 32, which is rigidly supported by suitable to the center of rotation of the abrasive wheel.

Abrasive is supplied to the housing- 43 by a i feed pipe 23 having its discharge end 23 extendflow of abrasive; furthermore, this prevents choking or clogging of the feed pipe 23.

Abrasive which is supplied to the housing 43 is forcibly ejected through the discharge opening I! by an impeller 33 comprising one or more vanes 3| carried by an end plate 32. The impeller vanes 3| extend inwardly to points short of the axis of rotation to provide a central space 33 into which the end 23 of the feed pipe preferably extends. The impeller 33 is mounted on a shaft 34 for rotation. which is suitably driven by a speed reducer 33 mounted on an arm 31 of the bracket 23. The speed reducer 33 may be driven from any suitable source of power (not shown) or if desired, a motor may be mounted on the bracket and directly connected to the shaft 34 in a manner generally similar to that shown in Fig. 10. In either case it is desirable that the impeller be driven at a variable speed, independently of the speed of rotation of the rotor.

The machine is operated by rotating the shaft 4 by means of a suitable source of power (not shown) at a suitable speed. For example, where the rotor is approximately 18 inches in diameter it will preferably be rotated at a speed of around 2200 to 2800 revolutions per minute and thus develop a blade tip velocity of from 10,000 to 15,000 feet per minute. Where the rotor is operated in these conditions and the impeller is driven at a suitable speed, abrasive supplied in an upward direction to the throwing blades at a position slightly above the axis of rotation will be picked up by the throwing blades and hurled therefrom adjacent their outer ends downwardly in a divergent fan-like stream. Other factors being suitably selected, the direction of the stream will be determined by the clock-dial position of the delivery of abrasive into the throwing blades relatively to the axis of rotation of the rotor and the direction of such delivery.

Where it is desired to change the direction of flight of abrasive from the throwing blades 3, the position of the control device I3 is adjusted accordingly. It will be noted that the shaft 2| is coaxial with the axis of rotation of the rotor and thus when the housing 43 is rotated about the axis of the shaft 2|, the discharge outlet turns about the axis of rotation of the rotor.

In Fig. the control device is shown as being disposed in a position rotated approximately 180 from the position illustrated in Fig. 2. It will be noted that the discharge outlet I1 is disposed below the axis of rotation of the rotor and the abrasive is discharged therefrom in a generally downward direction onto the blades I3. The machine as thus adjusted, if operated under the conditions above stated, will project a stream of abrasive in an upward direction and at approximately opposite the stream projected by the device as adjusted in Fig. 2.

The support is provided with an arm 38 having an opening 39 whereby, when the support 20 and housing 43 are rotated to the position shown in Fig. 5, the feed pipe can be removed from the opening 29 in the arm 28 and inserted in the opening 39 whereby it will be in a generally upright position.

In certain cases it is desirable to control the flow of abrasive so that it is delivered to the rotor at a point well within the interior of the rotor. An illustrative embodiment of such construction is illustrated in Figs. 6 to 9, to which reference now is made.

The machine comprises a rotor i0I including a side wall I02 carried on a shaft I03 for rotation, the side wall being preferably mounted on a shaft by a hub member I04 to which the side wall is rigidly connected as by bolts I05.

Supported by the side wall I02 is a series of throwing blades I06 extending inwardly from adjacent the periphery of the rotor to points inwardly short of the axis oi rotation, the inner ends of the blades-defining a central space I00. A second side wall I0? may be secured to the side wall I02 and the blades I06 are suitably secured to one or both of the side walls. The throwing blades preferably are seated in grooves formed in the side walls I 02 and I0? and abut a central block or plate I60 disposed in a central opening I in the side wall I02. The side wall it)? is formed with a central opening I09 providing access to the central space I08.

A control device I I0 is disposed adjacent the rotor WI and has a discharge outlet III within the rotor and adjacent the inner ends of the blades i06 in a position to deliver abrasive into the path of rotation of the blades. The control device IIO comprises a housing I disposed outside the rotor and having a nose or spout II2 extending through th opening I09 in the side wall I07 and into the space I08. The spout H2 has its end edge I I3 terminating closely adjacent the inner ends of the blades I06.

The housing I30 is carried by and preferably is integral with a mounting flange I3I which is adjustably mounted on a support I I9 by bolts I It extending through arcuate slots II6 in the support I Id. The bracket I3I is disposed closely adjacent the side wall I01 of the rotor IN and extends outwardly to thereby substantially close the opening I09, a sufilcient space being left, however, to permit clearance for the rotor IM and to permit the egress of any abrasive which is fed into the central space I06 and is not deposited on the blades I06. I

The discharge outlet III is offset radially from the axis of rotation of the rotor and the direction of discharge of the abrasive from outlet IN is inclined to the radii of the rotor in a sense toward the direction of rotation of the rotor whereby the abrasive has an initial velocity both outwardly along the throwing blades I06 and in the direction of rotation thereof.

Abrasive is supplied to the housing I30 through a feed pipe I20 having a spout I2I extending through an opening I22 in the side wall I31 of the housing I30. Disposed in the housing is an impeller I26 for accelerating the abrasive and hurling it through the discharge opening III. The impeller comprises one 01' more 'vanes I26 carried by an end plate I2I which in turn is supported on the shaft I28 for rotation. The shaft I28 is suitably driven by a speed reducer I 29 energized by a motor (not shown) or by a motor (not shown) connected directly to the shaft I28 in a manner generally similar to that shown in Fig. 10. In either case the drive for the impeller is such that its speed of operation can be adjusted.

The impeller vanes I26 extend inwardly from the periphery of the impeller and terminate short of the axis of rotation thereby providing a central space I3I' into which the delivery end I2I of the feed pipe may be extended whereby abrasive delivered by the feed pipe I20 is discharged adjacent the inner ends of the vanes I26.

The operation of this form of device is generally similar to the operation of the embodiment previously described. In this case, however, the spout I I2 extends entirely through the side plate I01 and into the central space provided by the blades I06. The abrasive thus is discharged directly onto the inner end portions of the throwing blades I06 over a limited are which is oifset radially from the axis of rotation of the rotor and in a direction inclined to the radius of the rotor.

The construction illustrated in Figs. 6 and 7 can be adjusted to direct the stream of abrasive from the rotor in any desired direction and at varying speeds of travel of abrasive. For example, in Fig. 8 the control device is illustrated as positioned with the axis of rotation of the impeller in a generally vertical direction, the control device being rotated from the position shown in Figs. 6 and 7. In this position the machine, if operated under certain conditions, such as specified above, will project the stream of abrasive in a direction approximately at a right angle to the direction of the abrasive provided by the adjustment shown in Figs. 6 and 7.

Referring now to Fig. 9, the machine is' shown as being adjusted for throwing the abrasive stream in a direction generally opposite to the direction in which the abrasive is thrown by the machine adjusted in the manner illustrated in Fig. 7. It will be noted that in Fig. 9 the control device is rotated approximately and the spout H2 is positioned so that the discharge outlet III is directed in a downward direction. In this arrangement it is convenientto invert the support I I8 as illustrated in Fig. 9, the mounting structure (not shown) for the support being suitably arranged for such inversion.

In certain cases it may be desirable to deliver the abrasive to the rotor at a point well within the interior of the rotor and to provide, a smooth, even flow of abrasive without abrupt change in direction or angularity of the fiow. One form of apparatus for effecting this result is illustrated inFigs. 10 and 11.

The machine comprises a rotor 20I including a side wall 202 mounted on a shaft 203 for rotation, the side wall being secured to the shaft in a suitable manner as by a hub member 206 to which the side wall isattached, as by bolts'205.

Carried on the side wall 202 is a series of throwing blades 206 seated in grooves 260 and extending from adjacent the periphery of the rotor to points inwardly short of the axis of rotation. The inner ends of the blades thus define a central space 201. A second side wall 208 may be secured to the side wall 202 in a suitable manner and the blades 206 secured to one or both of the side walls. The side wall 208 may be formed with an opening 20!! providing access to the inner ends 240 of the blades 206.

Disposed in the central space 20! is a deflector 2|0 suitably shaped to guide the abrasive smoothly into the path of the throwing blades. The deflector 2|0 preferably is inserted in a central opening 26| in the side wall 202 and serves as an abutment for the inner ends of the throwing blades 206.

For assisting in delivering the abrasive onto the throwing blades, one ormore deflector vanes 2|2 are provided on the deflector 2l0, which vanes preferably correspond in number and general location to the throwing blades 206. In order to further facilitate the smooth flow of the abrasive along the deflector vanes 2|2 and onto the throwing blades 206, the former preferably are disposed slightly in advance in an angular direction of the latter. Furthermore, each deflector vane 2|2 is formed with an arcuate base 246 and is curved both in a direction parallel to the plane of rotation and in a direction per pendicular to the plane of rotation of the rotor, as will be seen particularly from an inspection of Fig. 10. The deflector 2|0 may be formed with a front wall 2|3 provided with an opening 2, the front wall being flared outwardly toward the opening 2.

A control device 2|5 is provided for delivering abrasive to the deflector vanes 2|2 and has a dis-' charge outlet 2|6 adjacent the paths of the inner ends of the deflector vanes 2| 2.

The control device 2|5 includes a housing 2|! having a spout 2|3 extending through the opening 2 and terminating adjacent the inner ends of the blades 2|2. In order to provide a smooth, generally streamline flow of abrasive into the rotor, the spout 2! is formed with walls 2|9 and 220 having interior surfaces extending substantially in continuation of the corresponding interior surfaces of the deflector front wall 2|3, the central portion 2 of the deflector 2 l being cut away, as indicated at 24|, to accommodate the inner end of the wall 2|9. ,The spout is positioned so that the discharge outlet 2 I6 is offset from a radial line parallel to the direction of discharge of abrasive, and thus the abrasive is given an initial velocity inv the direction of rotation of the blades, as well as outwardly. The spout 2|8 preferably is arced in the direction of rotation of the rotor as illustrated particularly in Fig. 10, the walls 242 and 243 being suitably shaped'and the end edge 244 of the spout being generally arcuate as illustrated.

The housing 2 I! is suitably mounted in a rigid manner by a bracket 226 which latter carries a stud 22! adjustable in a bearing 228 and positioned as by a set screw 220. An additional support may be provided if desired. For example, the bracket 226 may be adjustably secured to a fixed arcuate member 262, as by a bolt 263, as illustrated in Fig. 11.

For the purpose of accelerating the abrasive so that it is hurled from the discharge outlet 2|6 at suitablevelocity, an impeller 230 is provided. The impeller 230 is formed with one or more vanes 23! carried by an end plate 232 which is mounted on a shaft 233 for rotation.

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The shaft 233 is suitably driven as by a variable speed motor 234 which may be supported on an arm 236 of the bracket 226. Abrasive is fed tothe impeller by a feed pipe 23! extending through an opening 238 in housing 2|! and terminating adjacent the impeller vanes 23! whereby abrasive ls delivered into the path of rotation of the impeller vanes.

The machine illustrated in Figs. 10 and 11 operates in a manner generally similar to that above described, the abrasive being delivered by the control device in a generally smooth, streamline flow to the throwing blades 206, owing to the shape and relative positions of the spout 2|6 and the deflector vanes 2|2. The spout 2|3 is so arranged that the abrasive is given not only an initial velocity radially of the rotor but also an initial velocity in the direction of rotation of the rotor. Thus the abrasive is delivered into the path of the throwing blades 206 with an initial velocity in the same general direction as it has after being deposited onthe blades, with the result that turbulence of the abrasive is minimized and a more effective action of the throwing blades on the abrasive is secured.

A modification of the construction shown in Figs. 10 and 11 is illustrated in Figs. 12, 13 and 14 to which reference now is made. The machine comprises a rotor including a side wall 302 mounted by a hub 304 on a shaft 303 for rotation. A plurality of blades 306 are carried by the 'side wall 302 and extend inwardly short of the axis of rotation to define a central space 303. A second side wall 30! having an opening 300, may

be provided and secured to the side wall 302 for the side wall 302 and is secured to the side wall Ill 302. A side wall 3|8 having an opening 3|0 may be provided at the outer ends of the deflector vanes 3|'!. The deflector vanes 3 I preferably are disposed in positions corresponding with the throwing blades but slightly in advance thereof, in the direction of rotation of therotor. The deflector vanes 3|! extend inwardly in a generally radial direction from adjacent the innerends of the throwing blades 306 to inwardly short of the axis of rotation of the rotor to define a central space 340. Each deflector vane 3|! is curved smoothly both in the direction of its length and in the direction of its width to assist in providing a smooth flow of abrasive onto the throwing blades 306.

A control device 3|5 is provided for delivering abrasive to the deflector vanes 3| 1 and has a d scharge outlet 322 terminating adjacent the path of the inner ends of the deflector vanes 3|!.

The control device 3|5 includes a housing 320 having a spout 362 defined by approximately parallel side walls 343 and 344 and arcuate side walls 323 and 324, which spout extends throu h the side wall opening 3|9 and into the central space 340. The housing 320 is suitably mounted on a bracket 33| having a stud 332 journaled in a mounting member 333 and adjustably secured therein by a screw 334. Additional support may be provided by an arm 363 extending from the bracket 33! and having its end flxedly hut adjustably held in a bracket 364.

For the purpose of accelerating the abrasive and delivering it through the discharge outlet 322, an impeller 323 is rotatably mounted in the housing 320 and has one or more vanes 32! car ried by an end plate 330 rotatably mounted by a shaft 35! driven by a motor 352 mounted on the bracket 33!. The impeller vanes 32! terminate inwardly short of the axis of rotation of the impeller 323 to provide a central space 323 and a feed tube 323 extends through the side wall of the housing 320, and preferably into the central space 328 for delivering abrasive to the impeller vanes 321.

The abrasive is hurled by the impeller 326 through the discharge outlet 322, the walls of the spout portion being positioned to direct the abrasive in a generally radial direction into the path of the abutments 3". In order that the abrasive will have an initial velocity in the direction of the movement of the blades, the discharge outlet 322 is ofiset from a radial line Parallel to the direction of flow of the abrasive from the discharge outlet, as illustrated in Fig. 13.

The inner ends of the deflector vanes 3|! preferably are spaced sufficiently from the end of the spout 362 to prevent abrasive which may enter between these members from grinding the surfaces thereof. Furthermore, to minimize any possible grinding action and to minimize interference with the passage of abrasive, the inner edges of the deflector vanes 3!! are thinned or tapered as shown.

The present invention provides an abrasive throwing machine wherein the rate and velocity of abrasive feed can be carefully controlled and adjusted over a large range. This adjustment is entirely independent of the speed of rotation of the rotor and thus a great range of control is obtainable. This adjustment can be accomplished without halting the rotor, and without necessitating the changing or replacement of any parts.

In the several forms of the invention illustrated, the discharge outlet of the control device is disclosed as being ofiset radially from the axis of rotation of the rotor and positioned so that the line of discharge of abrasive from the discharge outlet crosses the radii of the rotor in a sense in the direction of rotation. However, it is not always necessary to incline the direction of discharge and in certain cases, the several constructions can be so designed that the discharge outlet is offset radially and the abrasive is discharged from the discharge outlet radially of the rotor. Where the discharge outlet and the direction of discharge are selected as illustrated, the abrasive deposited in the path of rotation of the blades is given a velocity in the direction of rotation of the blades, which results in a more smooth and less turbulent flow of abrasive onto the blades, with less dispersionand spattering of abrasive. Also, there is less wear of the blades, less deterioration of the abrasive, and a closer control over the direction of flight of abrasive from the throwing blades.

While certain novel features of the invention have been disclosed herein, and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An abrasive throwing machine comprising a rotor including a plurality of throwing blades extending from adjacent the periphery toward the axis of rotation thereof, means mounting said to said rotor including a housing havmg a discharge outlet positioned to direct abrasive into the path of rotation of said throwing blades and oflset from the axis of rotation of said rotor, an impeller rotatable in said housing, means for rotating said impeller independently of said rotor in a plane angularly disposed with respect to the plane of rotation of said throwing blades, and means mounting said housing for angular adjustment about the axis of said rotor whereby to adjust the position of said discharge outlet relative to the axis of rotation of said rotor.

2. An abrasive throwing machine comprising a rotor including a plurality of throwing blades extending from adjacent the periphery toward the axis of rotation thereof, means mounting said rotor for rotation, means for feeding abrasive to said rotor including a housing having a discharge outlet adjacent the inner ends of said throwing blades, said discharge outlet being positioned to direct abrasive into the path of rotation of said blades so that the direction of discharge of abrasive from the discharge outlet crosses the radii in the sense of the direction of rotation of the rotor, an impeller rotatable in said housing, means for rotating said impeller independently of said rotor in a. plane angularly disposed with respect to the plane of rotation of said throwing blades, and means mounting said housing for angular adjustment about the axis of said rotor whereby to adjust the position of said discharge outlet relative to the axis of rotation of said rotor.

3. An abrasive throwing machine comprising a rotor having a plurality of throwing blades extending from adjacent the periphery towards the axis of rotation of the rotor, means for rotating said rotor, means including a duct for feeding abrasive into the path of rotation of said throwing blades at a point radially offset from the axis of rotation of said rotor and feeding means in said duct including a rotary impeller comprising vanes radially arranged about a central space, means for rotating said impeller independently of said rotor in a plane angularly disposed with respect to the plane of rotation of said blades, means for feeding abrasive into said central space of the impeller, and means mounting said abrasive feeding duct for angular adjustment about the axis of rotation of said rotor whereby to adjust the position of the discharge outlet of said duct relative to the axis of rotation of said rotor.

4. An abrasive throwing machine comprising a rotor having a plurality of throwing blades extending from adjacent the periphery toward the axis of rotation of the rotor, means mounting said rotor for rotation, means including a confined duct for depositing abrasive in the pathof rotation of said throwing blades at a predetermined point radially ofiset from the axis of rotation of said rotor and feeding means in said duct including a rotary impeller comprising vanes radially arranged about a central space, means for rotating said impeller independently of said rotor in a plane angularly disposed with respect to the plane of rotation of said blades, means for delivering abrasive into the space between the impeller vanes to the inner edges thereof, and means mounting said duct for angular adjustment about the axis of rotation of said rotor whereby to adjust the feeding position of the discharge outlet of said duct relative to the axis of rotation of said rotor.

5. An abrasive throwing machine comprising, a rotor including a plurality of abrasive throwing blades extending from adjacent the periphery inwardly toward the axis of rotation of said rotor, means mounting said rotor for rotation, a generally tubular impeller casing positioned exteriorly of said rotor, an abrasive impeller rotatably mounted within said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, means for rotating said impeller, means for supplying abrasive to said impeller casing, and an abrasive outlet port in the tubular wall of said casing arranged to direct a confined stream of abrasive thrown by said impeller into the path of rotation of said throwing blades at a predetermined point radially ofiset from the axis of rotation of said rotor.

6. An abrasive throwing machine comprising, a rotor including a plurality of abrasive throwing blades extending from adjacent the periphery inwardly toward the axis of rotation of said rotor, means mounting said rotor for rotation, a generally tubular impeller casing positioned exteriorly of said rotor, an abrasive impeller rotatably mounted within said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, means for rotating said impeller, means for supplying abrasive to said impeller casing, and an abrasive outletport in the tubular wall of said casing arranged to direct a conflned stream of abrasive thrown by said impeller into the path of rotation of said throwing blades at a predetermined point radially offset from the axis of rotation of said rotor and inclined to the radii of the rotor in a direction toward its direction of rotation.

7. An abrasive throwing machine comprising, a rotor including a plurality of generally radially arranged abrasive throwing blades extending inwardly short of the axis of rotation of said rotor to provide a central space, means mounting said rotor for rotation, a generally tubular impeller casing positioned exteriorly of said rotor, an-

abrasive impeller having a plurality of abrasive impelling vanes rotatably mounted wifiiin said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, a downwardly extending abrasive supply conduit for supplying abrasive to said impeller casing by gravity feed, and an abrasive outlet nozzle extending from the tubular wall of said casing having an abrasive discharge outlet positioned within said central space and adjacent the "path of rotation of the innerend of said throwing blades, said discharge outlet being offset radially from the axis of rotation of said rotor.

8. An abrasive throwing machine comprising, a rotor including a plurality of abrasive throwing blades extending from adjacent the periphery of the rotor inwardly toward the axis of rotation thereof, an abrasive deflector associated with the inner end of each of said throwing blades, a generally tubular impeller casing positioned exteriorly oi said rotor, an abrasive impeller rotatably mounted within said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, means for supplying abrasive to said impeller casing, an abrasive outlet port in the tubular wall of said casing shaped to direct a confined stream of abrasive thrown by said impeller into the path of rotation of said deflectors at a predetermined point radially offset from the axis of rotation of said rotor.

9. A centrifugal abrasive throwing machine comprising, a rotor including a plurality of abrasive throwing blades extending from adjacent the periphery of the rotor inwardly toward the axis of rotation thereof, a deflector vane associated with the inner end of each of said blades having a curved pick-up surface, a generally tubular impeller casing positioned exterlorly of taid rotor, an abrasive impeller rotatably mounted within said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, means for supplying abrasive to said impeller casing, an abrasive outlet nozzle extending from the tubular wall of said casing into the path of rotation of the inner ends of said deflectors operative to direct a confined stream of abrasive thrown by said impeller into the path of rotation of said deflectors at a predetermined point radially offset from the axis of rotation of said rotor.

10. An abrasive throwing machine comprising, a pair of interconnected generally parallel arranged side wall discs, a rotatably mounted shaft supporting said discs, a plurality of generally radially arranged abrasive throwing blades mounted between said discs and extending inwardly short of the axis of rotation thereof to provide a central space, a generally tubular impeller casing positioned exterior to said rotor but immediately adjacent thereto, an abrasive impeller rotatably mounted within said casing about an axis angularly disposed with respect to the axis of rotation of said throwing blades, a gravity feed conduit for supplying abrasive substantially centrally to said impeller, an abrasive outlet conduit in the tubular wall of said casing extending through an opening in the adjacent side wall disc of said rotor into said central space terminating adjacent the path of rotation of the inner ends of said blades, said conduit being operative to direct a confined stream of abrasive thrown by said impeller into the path of rotation of said blades at a predetermined point radially oflset from the axis of rotation of said rotor.

11. An abrasive throwing machine comprising, a rotor including a plurality of abrasive throwing blades extending from adjacent the periphery inwardly toward the axis of rotation of the rotor, means for rotating said rotor at abrading speeds, a generally tubular impeller casing positioned exteriorly of said rotor having a generally tubular shaped side wall and spaced end walls, an abrasive impeller positioned within said casing, a shaft fixed to said impeller extending through one of said end walls having its axis angularly disposed with respect to the axis of rotation of said throwing blades, means for rotating said impeller shaft, a gravity feed conduit extending intoan opening in the other side wall of said impeller casing for supplying abrasive to said impeller, and an abrasive outlet nozzle extending from said casing to a point adjacent the path of rotation of the inner ends of said throwing blades, said nozzle being operative to direct a confined stream of abrasive thrown by said impeller into the path of rotation of said throwing blades at a predetermined point radially offset from the axis of rotation of said rotor.

EDWARD R. HUGHES. 

